The present invention relates generally to roller-type map holders, which facilitate the storage and display of a map wound on the roller and, more particularly, to a compact, lightweight roller-type map holder which can be conveniently used in confined spaces and/or while traveling, such as in an automobile. In particular, the present invention relates to a roller-type map holder in which the roller and map are wound and unwound by a motor.
Typically, roller-type map holders either detachably or permanently mount a map on a roller. The roller, in turn, is mounted for rotation within a cylindrical or rectangular casing or housing. While such map holders may have no mechanized means for retracting the unwound roller/map, many if not most such map holders use spring rollers which are similar to those used in window shades. One example of such a roller is the spring and ratchet mechanism-controlled roller which is disclosed in Stout U.S. Pat. No. 1,723,820.
A number of approaches are also available for mounting the roller mechanism/map housing to a support surface such as the dash or windshield or sun visor of an automobile. For example, the housing may comprise or be mounted to a bracket which is fastened to an automobile dash, as by screws, as disclosed in Connors U.S. Pat. No. 1,065,295 and Richey U.S. Pat. No. 1,583,998. Alternatively, or in addition, resilient hooks or clips may be provided to temporarily attach the map housing to a windshield or sun visor, as disclosed in Vancil U.S. Pat. No. 1,570,104 and in Owen U.S. Pat. No. 2,188,612. Another approach, described in Hanks U.S. Pat. No. 1,588,106, uses resilient brackets or clips which are adapted both to fasten to a surface such as an automobile dash and to clip over an object such as a windshield.
As mentioned, the map can be permanently or detachably fastened or mounted to the roller. Relatively permanent fastening approaches include merely affixing the map to the roller, as by use of screws, or providing the map on or as part of a sleeve which is fastened to the roller by screws, as disclosed in Venard U.S. Pat. No. 1,364,223. Detachable fastening is provided, for example, by pointed spurs on the map roller as disclosed in the above-mentioned Vancil patent, or by the use of a map holding sheet which is attached to the roller and contains a pocket flap for holding the map. This latter approach is disclosed in the above-mentioned Richey patent. Alternatively, the map may have a tab or tongue which is removably wound into a longitudinal slot in the roller, as described in Seaquist U.S. Pat. No. 1,590,862 and in Hardt U.S. Pat. No. 2,180,146. Also, removable, unitary map-roller assemblies can be used. One such assembly is disclosed in the above-mentioned Stout patent.
It is one object of the present invention to provide a motor-driven roller-type map holder, in which a motor is used to unwind and rewind the roller-carried map. This approach is distinct from the window shade-type of spring roller used in the above-described patents, in which the shade or map is unwound manually and a coil spring effects rewinding.
It is another object of the present invention to provide a compact, completely self-contained roller-type map holder which has the advantage of being motor driven, but nonetheless is compact and lightweight and incorporates a relatively uncomplicated yet effective mounting arrangement for limiting the travel of the motor-driven map during winding and unwinding.
In one aspect, the map holder of the present invention includes a mounting frame in the form of a housing which supports and encloses a roller. The roller is mounted within the housing for rotation about a longitudinal axis and is adapted for fastening to a shade or map. Also mounted within the housing is a motor having a drive shaft which is operatively coupled to the roller for reversibly rotating the roller about its rotational axis to rewind and unwind the map.
In one preferred arrangement, both the motor and its energy source, in the form of batteries or a solar cell or solar cell(s), are contained within a compartment or compartments within the housing. Alternatively, in automotive-type applications, the motor can be direct wired to the vehicle's battery, particularly in OEM installations, or can be adapted to plug into the cigarette lighter.
In another preferred aspect, the housing is a unitary plastic structure and has a slot defined in one major face thereof, through which the shade or map extends and is wound and unwound. The slot is defined by a hinged door which provides access to the interior of the housing.
In another aspect, the motor drive shaft is operatively connected to the roller by a friction coupling so that, upon reaching a predetermined rotational torque, as when the map is unwound or fully rewound, the roller is decoupled from rotation with the motor. This prevents the application of excess stress to the map and the possibility of pulling the map loose from its mounting. The result of the various aspects described above is a motor-driven map holder which is compact, lightweight and convenient to use.